Semi-automatic telephone system.



A. E. LUNDELL. SEMI-AUTOMATIC TELEPHONE'SYSTEMV. APPLICATION FILED AUGJG. l9l6.

1,292,828. Patented Jan. 28, 1919 2 SHEETSSHEET l- /n van for: A/ben E. Lunde/l.

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SEMI-AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED AUGJB. 1916.

1,292,828. Patented Jan. 28, 1919.

2 SHEETSSHEET 2.

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Wrap STATES PATENT OFFICE.

ALIBEN E. IJUNDELII, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY,

INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

SEMI-AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Jan. 28, 1919.

Application filed August 16, 1916. Serial No. 115,210.

To all whom it may concern:

Be it known that I, ALBEN E. LUNDELL, a citizen of the United States, residing at New York, in the county of Bronx and State of New York, have invented certain new and useful Improvements in Semi-Automatic Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems, and more particularly to a two-way trunking arrangement by which connections may be established between manual and automatic exchanges.

The object of this invention is to provide means for preventing false display of the trunk signal if the manual operator is the first to disconnect. Unless some such means are provided, the same condition would exist as though a call were coming in to the manual operator from the automatic exchange.

It is thought that the invention will best be understood from the following detailed description, reference being had to the accompanyin drawings.

In the drawings, Figure 1 shows schematically the circuits at a semi-automatic oflice, while Fig. 2, which is to be placed to the right of Fig. 1, shows the circuits at a manual office connected to the semi-auto matic oflice by a two-wire trunk.

When the subscriber at substation 1 desires connection, he removes his receiver from the switchhook, whereupon a line signal 2 is displayed by the operation of a line relay 3 in the well-known manner. The operator at O inserts a plug 4 into a jack 5 associated with the calling line, whereupon a supervisory relay 6 is energized over the calling line circuit to prevent the display of a supervisory lamp 7 in the well-known manner. At the same time a cut-off relay 8 is energized over the sleeve contacts of the plug 4 and jack 5 to remove the control of the line relay andsignal from the calling subscriber.

The operator at 0 may now converse with the calling subscriber and learn the number of the wanted line. She then operates a sender to set a train of automatic switches indicated by brush sets 9, 10, 11 and 12, 13, 14, in the well-known manner. The controlling circuits for establishing this connection are set up by a sequence swltch as-- sociated with the operators connecting cord, such sequence switch not being shown in the present disclosure. The selector switches and sequence switches used in the present system are preferably similar in. construction and mode of operation to those shown in Patent No. 1,168,319, issued January 18, 1916.

When the brushes 12, 13 and 14 have been positioned on terminals 15, 16 and l7 of a two-way trunk leading to a manual office and the operators connecting cord sequence switch has arrived in its sixteenth position, a circuit is closed for a ringing relay 18 from grounded battery, winding of relay 18, armature and back contact of relay 19, armature and back contact of relay 20, sequence switch contact 21, closed in its sixteenth position, to ground. When brush 14 is positioned on terminal 17, a circuit is closed for relay 22 from grounded battery, winding of relay 22, conductor 23, terminal 17, brush 14, to ground. Relay 22 attracts its armatures and prepares a circuit by which the ringing current may be tripped. Ringing current is applied to the line from ground, generator 25, trip relay 20, lower armature and front contact of relay 18, brush 10, its terminal 26, brush 13 and its terminal 16, conductors 27, 28, armature and back contact of relay 29, armature and front contact of relay 22, to grounded battery. Suflicient current flows over this path to energize trip relay 20, which attracts its armature and removes the shunt path around relay 19, which then energizes in series with relay 18.

When relay 19 attracts its armature, it shunts out relay 18, which deenergizes and connects the talking strands of the connecting circuit to the trunk at its armatures and back contacts. At the same time the com necting cord sequence switch is moved, by means of circuits not shown, from its sixteeth to its eighteenth position, which is the talking position.

A circuit is now completed for trunk relay 59 from grounded battery, winding of relay 59, armature and back contact of cutofi' relay 30, trunk conductor 31, armature and back contact of relay 32, trunk conductor 33, terminal 15, brush 12, terminal 34, brush 9, upper armature and back contact of relay 18, upper right-hand winding of repeating coil 35, to ground. Relay 59, at

its armature and front contact, closes a circuit for a-trunk signal 36. The cord circuit shown at G is under the control of an operator in a manual exchange. When she notices the lighting of lamp 36, she inserts a plug 37 into a jack 38, whereupon a circuit is closed for relay 39 from ground, upper left-hand winding of repeating coil 40, supervisory relay 41, tip of plug 37, tip contact of jack 38, trunk conductor 42, winding of relay39, trunk conductor 27, terminal 16, brush 13,'terminal 26, brush 10, lower armature and back contact of relay 18, supervisory relay 43, lower right-hand winding of repeating coil 35, to grounded battery. Relay 39 at its armature and front contact closes a circuit for relay 29, which is energized. At the instant relay 39 pulls up, a circuit parallel to the energizing circuit for relay 29 is closed for relays 44 and 32 in series from grounded battery, winding of relay 44, lower armature and front contact of relay 22, winding of relay 32, to ground at the armature and front contact of relay 39. Relay 44 is energized, but its high resistance prevents the energization of relay 32.

Under this condition, relay 44 completes a holding circuit for itself from grounded battery, winding of relay 44, lower armature and front contact of relay 22, lower armature and front contact of relay 29, to ground at the armature and front contact of relay 44.

It may be noticed at this point that relays 22, 29 and 39, 44 remain energized until the connection is taken down. The operator at 0 may now converse withthe operator at O and informs her of the number of the wanted line. The operator at O then inserts a plug 45 into a jack 46 associated with the desired line. The connection is now When conversation is concluded, the operator at O is informed that the subscriber at substation 47 has replaced his receiver on the hook by the lighting of supervisory lamp 48, controlled by the denergization of relay 49 in the well-known manner. She thereupon removes plugs 45 and 37 from jacks 46 and 38 respectively. If the connection at O has not yet been destroyed, the trunk signal 36 will be lighted over the path which first caused its display, unless means are provided to prevent such action. is accomplished in the following manner.

The removal of the plug 37 from jack 38 caused the denergization of relay 39. Relays 29 and 32 are now energized in series over a path from grounded battery, windings of relays 29 and 32, lower armature and front contact of relay 29, to ground at the armature and front contact of relay 44. The energization of relay 32 opens the circuit over trunk conductor 31 by which trunk relay 59 was previously energized, and thus prevents the relighting of lamp 36.

When the connection at O is taken down, ground is removed from terminal 17 and relay 22 is denergized, breaking at its lower armature the holding circuit of relay 44. The release of relay 44 opens the circuit of relays 29 and 32. The apparatus is now in its normal condition. y

If we assume now that a subscriber at substation 47 desires connection to a subscriber at substation 1, the operation of the system is as follows. Connection to the manual operator at O is obtained in the usual manner. On learning the number of the wanted line, she then inserts plug 37 into jack 38, whereupon a circuit is completed for relay 44 from grounded battery, winding of relay 44, contact 55, conductor 50, trunk conductor 42, tip contact of jack 38, tip of plug 37, supervisory relay 41, upper left-hand winding of repeating coil 40, to ground. Relay 44 completes a circuit for trunk signal 51 from grounded battery, lamp 51, lower armature and back contact of relay 29, to ground at the armature and front contact of relay 44. The lighting of lamp 51 at tracts the attention of an operator whose position is indicated at O in the semi-automatic ofiice. She then inserts plug 52 into a jack 53 associated with lamp 51. The operator at 0 then converses with the operator at O, and on learning the number of the wanted line sets up the desired connection over a train of automatic switches to sub station 1.

The operation of relays 22, 29, 32, 39 and 44 from this point is identical with that previously described, excepting that relay 22 remains energized until the operator at O destroys the connectionover a path from grounded battery, winding of relay 22, conductors 23 and 24, sleeve contact of jack 53, sleeve of plug 52, resistance 54, to ground.

At the conclusion of conversation, the connection is taken down in the usual manner, the false display of trunk signal 36 being prevented as hereinbefore described.

Should the operator at 0 be the first to disconnect, lamp 51 willnot be lighted, since relay 29 is maintained energized until the operator at O removes plug 37 from jack 38,'at which time relay 44 is denergized and opens at its armature the circuit of relays 29 and 32.

What is claimed is:

1. In a telephone exchange system, an ofiice, an operators position thereat,asecond office, an operators position at such second office, a two-way trunk over which connections may be established between said ofiices, a trunk signal for notifying the operator at said second oflice that a connection has been made with said trunk, means to automati cally operate said signal as a result of the taking of said trunk for use, and means in said trunk circuit at said first office for preventing a false display of said signal if the operator at the second office is the first to disconnect.

2. In a telephone exchange system, an office, an operators position thereat, a second office, an operators position at said second office, a two-way trunk over which connections may be established between said oflices, trunk signals, one at each end of said trunk, for notifying the operator at either ofiice that a connection has been made with said trunk at the other one of said ofiices, means to automatically'operate the signal at the incoming oflice as a result of the taking of said trunk for use, and means in saidtrunk circuit for preventing the false display of either one of such trunk signals at whichever office is first to disconnect.

3. In a telephone exchange system, a semiautomatic ofiice, an operators position thereat, a manual office, an operators position at such manual oiiice, a two-way trunk over which connections may be established be tween said ofiices, atrunk signal for notifying the operator at said manual ofiice that a connection has been made with said trunk, means to automatically operate said signal as a result of the taking of said trunk for use, and means controlled over the conductors of said trunk circuit for preventing a false display of such signal if the manual operator is the first to disconnect.

4:. In a telephone exchange system, a semiautomatic ofiice, an operators position thereat, a manual ofiice, an operators position at such manual office, a two-way trunk over which connections may be established between said oflices, trunk signals for notifying the operator at either office that a connection has been made with said trunk at said other office, means for automatically causing the display of the signal at the incoming end of said trunk as a result of the taking of said trunk for use, and means in said trunk circuit for preventing the false display of either one of such trunk signals at whichever oflice is first to disconnect.

5. In a telephone exchange system, a semiautomatic ofli'ce, an operators position thereat, a manual office, an operators position at such manual oflice, a two-way trunk over which connections may be established between said ofiices, automatic ringing means associated with said semi-automatic oflice for applying ringing cu1."rent to a desired line, means for cutting off such ringing current when connection is established to a trunk terminating in said manual oiiice, a trunk signal for notifying the operator at said manual office that a connection has been made with said trunk, and means for preventing a false display of such signal if the manual operator is the first to disconnect.

6. In a telephone exchange system, a semiautomatic oflice, an operators position thereat, a manual oflice, an operators position at such manual office, a two-way trunk over which connections may be established between said ofli'ces, a trunk signal for notifying the operator at said manual office that a connection has been made with said trunk, a relay for controlling said trunk signal, means whereby the false display of said signal is prevented if the manual operator is the first to disconnect, said meansincluding a second relay in series with one side of said trunk, and a third relay controlled by said second relay, said third relay controlling at its armature the path over which said first relay is energized.

In witness whereof, I hereunto subscribe my name this 15th day of August A. D.,

ALBEN E. LUNDELL.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, I). 0." 

